In addition to packing on pounds and boosting overall cancer risk, booze boosts activity of an enzyme called aromatase, which converts other hormones into estrogen. “For any increase in alcohol use, there is a linear increase in breast cancer risk,” says Pendergrast. According to AICR, five drinks per week boosts a woman’s risk by 5 percent; two or more drinks per day skyrockets risk by more than 40 percent. So if you like the occasional cocktail, keep it below five a week. Or, if you have a strong family his- tory of the disease, consider teetotaling.